Delay detonator design

P4 explosives were specifically designed for the operation of ripping with delay detonators (see p. 143) and must satisfy the following tests ... 

Delay detonators for use in coal mines must be constructed so as not to ignite methane/air mixtures even if iired accidentally outside a cartridge of a blasting explosive. This requires a suitable selection of fusehead and the provision of the delay element in a form which will not produce large particles of hot slag on burning. In the British design the delay elements are... 

Fordham (Ref 51, p 127) states that a common mixture for US delay elements consists of Ba peroxide 85 Se 15% and that for the manuf of millisecond delay detonators, faster burning compns are required such as Si 30-50 red lead (or lead dioxide) 50-70%. Manuf of delay compns is described on pp 128-29, assembly on p 129 and design on pp 129 30 of Ref 51. Ger delay compositions (Verzo-gerungsverbindungen) and delay elements(Verzo-gerungskorper) are described In Ref 35, pp Ger 33 Ger 34... 

In the design of the detonator attention must also be paid to the effects of the liberation of gas which, though small, is still sufficient to require attention. As the speed of the delay composition is affected by pressure, it is necessary that the free space in the detonator should be carefully controlled. Also, the plug which seals the leading wires in place must withstand this pressure for more than the delay period of the detonator. This task is made more difficult by conduction, along the metal walls of the detonator shell, of heat liberated by the fusehead and the delay composition. Plastic plugs in particular are liable to soften and be ejected from the detonator with probable failure of burning of the delay column. 

This type of detonator is designed to deliver a detonating impulse when acted upon by a heat impulse or a detonating impulse generated by a previous element. In the latter case it serves for boostering the detonating impulse. Heat impulses may result from the flash of a delay element in delay type fuzes or the flash from a primer in instantaneous type fuzes. When initiation results from the functioning of a previous detonator, the flash type detonator usually serves in the capacity of a relay where the gap over which the detonation must be transmitted is too... 

They extend from BT 0.01 to 18 sec/in. When in loose form some of them burn very violently Formulas 193, 194 195, designated as Delays for Detonators ", are described by D.T. Zebree in USP 3113519 (1963). They are used in combinations with Pb/Se and Pb/Te ignition mixts, which are not listed in Ellem s books 1961 ... 

Fuze, Hand Grenade. A pyrotechnic delay fuze initiated by release of a lever which in turn permits a striker to impinge on a primer. The output of the fuze is designed to ignite or detonate a filler of a hand grenade... 

A bomb primer-detonator is an interchangeable unit (composed of a primer delay element and a detonator) which is designed to provide delay in the action of older models of tail fuzes. Primer-detonators of various time delays are available, with the exact delay time of each painted on the detonator head (Ref 51 a,... 

Delay-Relay Element. It is a component of HE train which introduces a delay in the time of functioning of the fuze. The delay element is always followed by a relay and the two are really one unit. The relay is an expl (such as BkPdr) designed to provide continuity of the expl train by picking up the weak flash from the delay element and augmenting it sufficiently to initiate, by detonation, a succeding component. The delay-relay element is located in the fuze of a projectile betw the percussion primer and the detonator (Ref 1)... 

Detonator Assemblies, Non-Electric for blasting Non-electric detonators assembled with and activated by such means as safety fuse, shock tube, flash tube or detonating cord. The[y] may be of instantaneous design or incorporate delay elements. Detonating relays incorporating... 

Detonators Articles consisting of a small metal or plastics tube containing explosives such as lead azide, PETN or combinations of explosives. They are designed to start a detonation train. They may be constructed to detonate instantaneously, or may contain a delay element. The term includes Detonators for Ammunition and Detonators for blasting, both Electric and Non-Electric. Detonating relays without flexible detonating cord are included. UN App. B, ICAO A2... 

There are times when one or two other elements are added to ihe explosive train. One such element is a delay, which is designed to prevent detonation of the booster for a specific period of time after the primer has been fired. The other is a relay which may be needed to strengthen the shock wave of the delay so that the booster ox secondary explosive can be initiated. 

Priming compositions or priming mixtures are sensitive explosive mixtures that are designed to produce a flame in a particular application. They are most often mixtures containing a primary explosive as one of the components in such a form and amount that ensures the inability to initiate detonation of the mixture. The role of the primary explosive is to sensitize the mixture to external stimuli, not to make it detonatable. Priming mixtures are used in percussion caps for ignition of gun powder, on electric fuseheads, delay elements, etc. 

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